Ion implantation is a physical process, as opposed to diffusion, which is a chemical process that is employed in semiconductor apparatus fabrication to selectively implant dopant into a semiconductor workpiece and/or wafer material. Thus, the act of implanting does not rely on a chemical interaction between a dopant and the semiconductor material. For ion implantation, dopant atoms/molecules are ionized and isolated, sometimes accelerated or decelerated, formed into a beam, and swept across a workpiece or wafer. The dopant ions physically bombard the workpiece, enter the surface and typically come to rest below the workpiece surface in the crystalline lattice structure thereof.
In RF based accelerators and DC based accelerators, ions can be repeatedly accelerated through multiple acceleration stages of an accelerator. For example, RF based accelerators can have voltage driven acceleration gaps. Due to the time varying nature of RF acceleration fields and the multiple numbers of acceleration gaps there are a large number of parameters, which influence the final beam energy. Because the charge state distribution of an ion beam can change, substantial effort is paid to keep the charge value in the ion beam at the initially intended single value. However, greater demands for an implantation recipe (e.g., ion beam energy, mass, charge value, beam current and/or total dose level of the implantation) at a higher energy level call for providing a higher beam current without compromising the ion source unnecessarily.
Accordingly, suitable systems or methods for increasing beam current are desired.